[1.12.x] Mark IV Spaceplane System (August 18, 2024)

sh1pman · March 31, 2017

Can't think of any. Maybe it'll break existing crafts?

Calvin_Maclure · March 31, 2017

8 minutes ago, sh1pman said:

Can't think of any. Maybe it'll break existing crafts?

Craft breakage, if at all possible, should be avoided. But id rather have it for the sake of a better mod than not.

Wyzard · March 31, 2017

1 hour ago, Nertea said:

Is there any reason NOT to do this?

I don't entirely know what I'm talking about here, but I think I've read that a part can't have more than one module that holds the same resource. That might mean you can't have both the main and side tanks configured for the same kind of fuel.

Operation40 · March 31, 2017

cool.. good to hear! btw: I did put my broadsword cfg at 8.0t / 420 / 720
so, math-wise that's no apparent gain over 4x rapiers, but really there is, if you consider the 200kg quad-coupler I'd use to mount those on a 2.5m stack..
I didn't mess with drag or fuel at all, and was happy with the results

If I understand you right; I don't mind simplifying the tank types (lobes?) at all.. " Just one tweakable for main tank (LF, LF/O) and one for the lobe tanks (Structural, LF, LF/O, Mono)" .. sounds perfect to me, indeed I see no reason not to do this...

*edit* oh,, breaking existing crafts.. I don't mind.. bring it on!

Edited March 31, 2017 by Operation40

AmpCat · March 31, 2017

@Nertea, I mentioned this on the KA thread, but wanted to chime in here about the possibility of atmosphere-breathing nuclear jet engines. Perhaps augmented by LH2, even.

As you probably know, historically, this was a thing; but at the time (the 60's, I believe), science struggled with materials and other advancements. These days most of these problems have been solved, so they should be fairly viable. Is this in scope, and should I add it to your git repository, or let it go for now?

Kobymaru · March 31, 2017

Silly question, but shouldn't bigger engines be more efficient than smaller engines, inherently?

HoveringKiller · March 31, 2017

29 minutes ago, Kobymaru said:

Silly question, but shouldn't bigger engines be more efficient than smaller engines, inherently?

Maybe, but they also burn more fuel for more power. I know in space, the size and shape of the bell is also an important factor. Exhaust speed I'm pretty sure is the largest factor however. I am not a rocket scientist however, so take what I'm saying with a grain of salt.

Calvin_Maclure · March 31, 2017

22 minutes ago, HoveringKiller said:

Maybe, but they also burn more fuel for more power. I know in space, the size and shape of the bell is also an important factor. Exhaust speed I'm pretty sure is the largest factor however. I am not a rocket scientist however, so take what I'm saying with a grain of salt.

You're on the right track. The magic of a rocket engine (and supersonic jet engines as well) is the converging-diverging nozzle. Thrust is produced via the acceleration of the gases, and that acceleration primarily and majorly occurs in the diverging part of the conv-div nozzle (i.e.: the bell shape). Basically, at the point of convergence, the flow becomes supersonic and the diverging section then continues to accelerate it*. One of the limiting factors is the back pressure** (i.e. the pressure of the surrounding env, which in space is null), so depending on what env you're designing the engine for (i.e.: where do you want it to perf at its best), your bell shape will vary accordingly. The bigger the bell nozzle, the greater the acceleration of the gases is, provided the back pressure is low enough. That's why in space with a null value back pressure (P_space = 0 psi or Pa), you can have rather large bell shapes for small engines. You accomplish greater gas exit velocity and thus thrust. Its all about showckwave manipulation. Believe it or not, this is actually how the diverging part of a conv-div nozzle manages to accelerate gases.

* - in subsonic flows, acceleration is produced via a converging shape. But once a flow reaches supersonic (M = 1), this rule changes and a diverging shape is then required to continue to accelerate the flow passed M=1.
** - this is the reason why engine's isp (specific impulse) actually increases with altitude. The higher you get, the lesser the surrounding pressure is due to diminishing density.

Edited March 31, 2017 by Calvin_Maclure
fixed typo

Nertea · March 31, 2017

15 hours ago, Wyzard said:

I don't entirely know what I'm talking about here, but I think I've read that a part can't have more than one module that holds the same resource. That might mean you can't have both the main and side tanks configured for the same kind of fuel.

Urk, I thought B9PartSwitch would get around this but looks like no.

Would anyone complain about not being about to store anything but MP in the lobe tanks anymore (ie, store nothing (no mass penalty) or MP)?

16 hours ago, Calvin_Maclure said:

Craft breakage, if at all possible, should be avoided. But id rather have it for the sake of a better mod than not.

Craft breakage is an unfortunate casualty of all the current rebalancing ;).

14 hours ago, AmpCat said:

@Nertea, I mentioned this on the KA thread, but wanted to chime in here about the possibility of atmosphere-breathing nuclear jet engines. Perhaps augmented by LH2, even.

You should check the git first before asking if you can put it on git... because this has been up there for a while: https://github.com/ChrisAdderley/MkIVSystem/issues/5

Operation40 · April 1, 2017

I'm going to comment on drag (sorry!)
Working on some math, but I suspect drag is up to 30% too high on mk4 parts. Right now, it seems roughly double the equivalent mk3 parts

http://steamcommunity.com/sharedfiles/filedetails/?id=895659075
The VAB is also reporting the mk4 bay is 10.7m wide.. This might be the cause of drag too? (edit - oh duh, it is 10.7m wide, with the bay doors open.. doh)

Currently looking for an online calculator that will help me prove me theory with MATH ! (queue dramatic music)

Edited April 1, 2017 by Operation40

damerell · April 1, 2017

38 minutes ago, Operation40 said:

Working on some math, but I suspect drag is up to 30% too high on mk4 parts. Right now, it seems roughly double the equivalent mk3 parts

That doesn't seem totally implausible given the relative cross-sections.

@Nertea I hate to say it, but presumably for purely atmospheric flights "more LF" is wanted, not monoprop-or-nothing. :-(

Operation40 · April 1, 2017

ahh I think I found it (without complicated math)
DRAG_CUBE "A" and "B" are the same for all mk4 cargo bay sizes.. So.. (not talking shielded/unshielded here), but the drag coefficient (a.CD) does not change when you open the bay vs closing it.

.. from mk4cargo-3.cfg.. CUBE A and B *were* both the same, I updated CUBE B, now the "A.CD" number drops a good bit when I close the bay

		cube = A, 10.29,0.6791,4.019, 
				10.29,0.6774,4.019, 
				23.47,0.9617,0.3096, 
				23.47,0.9611,0.2989, 
				19.63,0.8969,1.774, 
				19.63,0.8502,2.534, 
				-0.0003667,0.002363,-0.3819, 
				7.87,2.522,4.108
		cube = B, 7.0965,0.6791,4.019, 
				7.0965,0.6774,4.019, 
				23.47,0.9617,0.3096, 
				23.47,0.9611,0.2989, 
				19.63,0.8969,1.774, 
				19.63,0.8502,2.534, 
				-0.0003667,0.002363,-0.3819, 
				7.87,2.522,4.108

Operation40 · April 1, 2017

ok here's all my updated numbers for those interested (I'm only showing the first 2 triplets from each set, the rest are unchanged):

mk4cargo-1.cfg

cube = A, 41.11,0.68,3.767, 
	41.11,0.6784,3.767, 
cube = B, 29.11958,0.68,3.767, 
	29.11958,0.6784,3.767,

mk4cargo-2.cfg

cube = A, 20.64,0.6766,4.019, 
	20.64,0.6748,4.019, 
cube = B, 14.5147,0.6766,4.019, 
	14.5147,0.6748,4.019,

and of course mk4cargo-3.cfg I posted earlier:

cube = A, 10.29,0.6791,4.019, 
	10.29,0.6774,4.019, 
cube = B, 7.0965,0.6791,4.019, 
	7.0965,0.6774,4.019,

this means there's a difference now in drag when you close the bay vs having the doors open.
I extrapolated numbers from the mk3 cargo set.. I imagine the tail bay and service bay need some love too

AmpCat · April 1, 2017

9 hours ago, Nertea said:

You should check the git first before asking if you can put it on git... because this has been up there for a while: https://github.com/ChrisAdderley/MkIVSystem/issues/5

Well, I feel sheepish. :blush:

Nertea · April 1, 2017

15 hours ago, Operation40 said:
ok here's all my updated numbers for those interested (I'm only showing the first 2 triplets from each set, the rest are unchanged):

mk4cargo-1.cfg
cube = A, 41.11,0.68,3.767, 
	41.11,0.6784,3.767, 
cube = B, 29.11958,0.68,3.767, 
	29.11958,0.6784,3.767, 
mk4cargo-2.cfg
cube = A, 20.64,0.6766,4.019, 
	20.64,0.6748,4.019, 
cube = B, 14.5147,0.6766,4.019, 
	14.5147,0.6748,4.019, 
and of course mk4cargo-3.cfg I posted earlier:
cube = A, 10.29,0.6791,4.019, 
	10.29,0.6774,4.019, 
cube = B, 7.0965,0.6791,4.019, 
	7.0965,0.6774,4.019, 
this means there's a difference now in drag when you close the bay vs having the doors open.
I extrapolated numbers from the mk3 cargo set.. I imagine the tail bay and service bay need some love too

I need you and possibly one other tester to verify that this doesn't break bay occlusion again before I go back to those numbers.

Operation40 · April 1, 2017

10 minutes ago, Nertea said:

I need you and possibly one other tester to verify that this doesn't break bay occlusion again before I go back to those numbers.

Great point -- I'll take another look to see if I broke that. Before I do that though, seems I was going about that the hard way.
The game auto generates the correct cube "a" and "b" and puts it in PartDatabase.cfg..
PartsDatabase.cfg

	url = MarkIVSystem/Parts/Fuselage/mk4cargo-3/mk4cargo-3
	DRAG_CUBE
	{
		cube = A, 10.25,0.6837,6.393, 10.29,0.6793,6.393, 5.926,0.956,1.356, 5.926,0.9526,1.356, 19.63,0.897,1.774, 19.63,0.8474,2.534, -0.0003664,0.002363,-0.3822, 7.87,2.522,4.108
		cube = B, 12.39,0.7291,10.74, 12.44,0.7287,10.74, 6.065,0.9554,1.356, 6.065,0.952,1.356, 26.41,0.8319,4.929, 26.43,0.8792,5.509, -0.0009923,0.002363,-1.072, 10.72,2.522,5.487
	}

This is quite a bit different than what I had, but it produces good results (drag coefficient increases with doors open, decreases with them closed). I think I'm going to refresh the numbers for all bays from the PartsDatabase.cfg, then yah, double check the occlusion.

I'm also looking at this possible issue: http://steamcommunity.com/sharedfiles/filedetails/?id=896257108
any part attached to a cargo bay (except another bay) acts like it's at the front of the stack (almost).. For instance, using a Drone Core for the tail workaround was showing 400kN+ of drag @ 300m/s (under 1km). That's not quite as bad as if it were at the front, but waaay too much for being an aerodynamic piece on a stack the same size. My suspicion is it is a "3 node stack" problem.. Imagine a stack of 5m tanks with 1.25 shoulder tanks, but instead of connecting nodes end-to-end on the shoulders you have them all connected radially to each's 5m tank.. of course given that these are just 1 piece parts and I can't connect 3 nodes at once, I'm going to disable the shoulder nodes all thru a craft to test the theory...

Nertea · April 1, 2017

2 hours ago, Operation40 said:
Great point -- I'll take another look to see if I broke that. Before I do that though, seems I was going about that the hard way.
The game auto generates the correct cube "a" and "b" and puts it in PartDatabase.cfg..
PartsDatabase.cfg
	url = MarkIVSystem/Parts/Fuselage/mk4cargo-3/mk4cargo-3
	DRAG_CUBE
	{
		cube = A, 10.25,0.6837,6.393, 10.29,0.6793,6.393, 5.926,0.956,1.356, 5.926,0.9526,1.356, 19.63,0.897,1.774, 19.63,0.8474,2.534, -0.0003664,0.002363,-0.3822, 7.87,2.522,4.108
		cube = B, 12.39,0.7291,10.74, 12.44,0.7287,10.74, 6.065,0.9554,1.356, 6.065,0.952,1.356, 26.41,0.8319,4.929, 26.43,0.8792,5.509, -0.0009923,0.002363,-1.072, 10.72,2.522,5.487
	}
This is quite a bit different than what I had, but it produces good results (drag coefficient increases with doors open, decreases with them closed). I think I'm going to refresh the numbers for all bays from the PartsDatabase.cfg, then yah, double check the occlusion.

I'm also looking at this possible issue: http://steamcommunity.com/sharedfiles/filedetails/?id=896257108
any part attached to a cargo bay (except another bay) acts like it's at the front of the stack (almost).. For instance, using a Drone Core for the tail workaround was showing 400kN+ of drag @ 300m/s (under 1km). That's not quite as bad as if it were at the front, but waaay too much for being an aerodynamic piece on a stack the same size. My suspicion is it is a "3 node stack" problem.. Imagine a stack of 5m tanks with 1.25 shoulder tanks, but instead of connecting nodes end-to-end on the shoulders you have them all connected radially to each's 5m tank.. of course given that these are just 1 piece parts and I can't connect 3 nodes at once, I'm going to disable the shoulder nodes all thru a craft to test the theory...

So before you get too far with the first one, you need to understand how the game calculates stack occlusion between parts. It subtracts the corresponding stack areas, so you can't just take the auto-generated values from the cargo bays and use them. They do need to be edited so that the +/- Y facing drag components are the same as a solid fuselage, so the drag can be properly subtracted. If you don't do that the game will think that a cargo bay in front of a fuselage is smaller than it is in cross-sectional area, and thus not subtract the drag properly.

That to me looks like what's going on in that screenshot.

@Operation40 sorry if I sound snarky by the way... I'm really glad you're actually experimenting and testing this.

Edited April 1, 2017 by Nertea

Operation40 · April 1, 2017

2 hours ago, Nertea said:

That to me looks like what's going on in that screenshot.

You nailed it.. I went back to the numbers from my earlier post and it cleared up the high drag I was seeing adjacent the bays..
re-tested occlusion, looks good : http://steamcommunity.com/sharedfiles/filedetails/?id=896484022

Operation40 · April 1, 2017

I have my tailbay shielding working!!! without the Drone Core in-between it and the other bays, and without toggling all bays at the same time:
http://steamcommunity.com/sharedfiles/filedetails/?id=896494089

mk4cargotail-1.cfg

node_stack_bottom2 = 0.0, -2.162734, 0.00, 0.0, 1.0, 0.0, 3
...
MODULE
	{
		name = ModuleCargoBay
		DeployModuleIndex = 0
		closedPosition = 1
		lookupRadius = 4
		nodeOuterForeID = bottom1
		nodeInnerForeID = bottom2
		
	}

I updated closedPosition to "1" instead of "0", which I think is what fixed it
also added an "inner" connection node that was missing
This cfg is missing a drag_cube definition.. not sure it makes a huge difference but the mk3 tail bay has a cube "a" and "b"

Operation40 · April 2, 2017

did some tailbay testing with my updated settings
tail bay closed: http://steamcommunity.com/sharedfiles/filedetails/?id=897075114
tail bay open: http://steamcommunity.com/sharedfiles/filedetails/?id=897075261
looks pretty good.. arguably a couple of those dawn engines should clip outside but.. meh.. it's Kerbal tradition to have a little room to cheese part placement.

Elethiomell · April 2, 2017

Thanks for your great work on this mod, thought I'd post a creation here and say thanks, I donated you some moneys as you richly deserve it :-) I am also having drag issues and I think an issue with the vulture cockpit overheating, possibly due to the service bay, but have no idea how to do a bug report so will leave that to other more skilled individuals.
This is a long-range science vessel with a tylo heavy lander, a rover and two resource scanner probes, also mining equipment, has about 6000DV once in LKO and can of course refuel.

http://steamcommunity.com/profiles/76561198008839012/images/

Nertea · April 3, 2017

On 4/2/2017 at 9:47 AM, Operation40 said:

did some tailbay testing with my updated settings
tail bay closed: http://steamcommunity.com/sharedfiles/filedetails/?id=897075114
tail bay open: http://steamcommunity.com/sharedfiles/filedetails/?id=897075261
looks pretty good.. arguably a couple of those dawn engines should clip outside but.. meh.. it's Kerbal tradition to have a little room to cheese part placement.

So an issue I had before with wide cargo definition areas was that engines mounted on the shoulder nodes were occluded. How is that working with your values?

On 4/2/2017 at 1:00 PM, Elethiomell said:

Thanks for your great work on this mod, thought I'd post a creation here and say thanks, I donated you some moneys as you richly deserve it :-) I am also having drag issues and I think an issue with the vulture cockpit overheating, possibly due to the service bay, but have no idea how to do a bug report so will leave that to other more skilled individuals.
This is a long-range science vessel with a tylo heavy lander, a rover and two resource scanner probes, also mining equipment, has about 6000DV once in LKO and can of course refuel.

http://steamcommunity.com/profiles/76561198008839012/images/

Thanks for the donation, I alway really appreciate that.

You're going to have to help me more with the last one because I've had this on my git: https://github.com/ChrisAdderley/MkIVSystem/issues/15 forever and can't reproduce it effectively. Craft pictures, reliable steps to reproduce, mod lists, etc.

Edited April 3, 2017 by Nertea

Beetlecat · April 3, 2017

On 3/19/2017 at 5:59 AM, Starslinger999 said:

Thats Literately what I just said

Also I am having trouble making my TB2 Fly because the "Wings" are so tiny. Wish there was Body Lift for deez

And the TB2 was nearly/literally the inspiration for these parts. :wink:

Operation40 · April 3, 2017

1 hour ago, Nertea said:

So an issue I had before with wide cargo definition areas was that engines mounted on the shoulder nodes were occluded. How is that working with your values?

I don't see any issues with the shoulder engines -- keep in mind, for the tailbay, I did not add/modify the drag_cube -- it's missing that definition and I left it alone.
the changes I made were the closedPosition=1 and adding the interior node
tailbay shoulder engine test, tailbay closed: http://steamcommunity.com/sharedfiles/filedetails/?id=898003899
tailbay shoulder engine test, tailbay open: http://steamcommunity.com/sharedfiles/filedetails/?id=898003945

Nertea · April 3, 2017

16 minutes ago, Operation40 said:

I don't see any issues with the shoulder engines -- keep in mind, for the tailbay, I did not add/modify the drag_cube -- it's missing that definition and I left it alone.
the changes I made were the closedPosition=1 and adding the interior node
tailbay shoulder engine test, tailbay closed: http://steamcommunity.com/sharedfiles/filedetails/?id=898003899
tailbay shoulder engine test, tailbay open: http://steamcommunity.com/sharedfiles/filedetails/?id=898003945

Oh, I thought you'd modified the cargo bay radii. That's fine then. I'll test those changes on my end then.

[1.12.x] Mark IV Spaceplane System (August 18, 2024)

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